Thermoreversible gels in oil/EVA systems

In this work we investigate the gel formation of EVA/recycled motor oil sys tems as a route to obtain synthetic binders which could be used instead of natural bitumen, as well as mixed with natural bitumen to modify adequately its viscoelastic response. The EVA. copolymer studied in this work has a vinyl acetate content of 18 w t% and solutions of EVA/motor oil have been prepared up to a concentration of 50 wt%. Dynamic viscoelastic frequency sweeps between 10(-2) Hz and 10(2 ) Hz have shown that above 3 wt%, at 25 degreesC, EVA/motor oil systems for m gels. It has been possible to define an elastic equilibrium modulus, G(e) , for each gel. The dependence of G(e) on concentration has been compared w ith that of PVC/DOP and SBS/oil gels on the basis of the De Gennes model. T hermal stability of EVA/motor oil gels has also been analyzed, indicating t hat for the highest polymer concentrations gel point is above 80 degreesC.